Screwdriver with dual cam slot for collated screws

ABSTRACT

A screwdriver for driving collated screws including a slide body coupled to a housing for reciprocal displacement in a cycle including a retraction stroke and an extension stroke. A lever pivotably mounted to the slide body carries at one end a cam pin received in a cam slot in the housing with the other end of the lever advancing successive screws in the screwstrip, the cam slot having first and second camming surfaces for selective engagement by the cam pin to vary the relative positioning of the lever to be different for the same position if the slide body in the housing in the retraction strokes than in the extension stroke.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.08/882,323 filed Jun. 25, 1997, now issued as U.S. Pat. No. 5,934,162,which is a continuation-in-part of U.S. patent application Ser. No.08/673,398 filed Jun. 28, 1996 now issued as U.S. Pat. No. 5,927,163,which is a continuation-in-part of U.S. patent application Ser. No.08/511,945, filed Aug. 7, 1995, now issued as U.S. Pat. No. 5,568,753,which is a continuation-in-part of U.S. patent application Ser. No.08/233,090 filed Apr. 28, 1994, now abandoned, which is acontinuation-in-part of U.S. patent application Ser. No. 08/198,129filed Feb. 17, 1994, now issused as U.S. Pat. No. 5,469,767, which is acontinuation-in-part of U.S. patent application Ser. No. 08/018,897filed Feb. 17, 1993, now issued as U.S. Pat. No. 5,337,635.

SCOPE OF THE INVENTION

This invention relates generally to a screwdriver for driving collatedscrews which are joined together in a strip, and, more particularly, toa power screwdriver with a nose portion which renders the screwdriveradaptable for use in driving screws having different lengths anddiameter screw heads.

BACKGROUND OF THE INVENTION

Collated screwstrips are known in which the screws are connected to eachother by a retaining strip of plastic material. Such strips are taught,for example, by U.S. Pat. No. 4,167,229 issued Sep. 11, 1979 and itsrelated Canadian Patents 1,040,600 and 1,054,982 as well as U.S. Pat.No. 4,930,630, the disclosures of which are incorporated herein byreference. Screws carried in such screwstrips are adapted to besuccessively incrementally advanced to a position in alignment with andto be engaged by a bit of a reciprocating, rotating power screwdriverand screwed into a workpiece. In the course of the bit engaging thescrews and driving it into a workpiece, the screw becomes detached fromthe plastic strip leaving the strip as a continuous length.

In the use of such collated screwstrips in screwdrivers, the stripserves a function of assisting in guiding the screw into a workpieceand, to accomplish this, the strip is retained against movement towardsthe workpiece. In the screwstrip, each screw to be driven has itsthreaded shaft threadably engaged in a threaded sleeve of the strip suchthat on the screwdriver engaging and rotating each successive screw, thescrew turns within the sleeve which acts to guide the screw as it movesforwardly into threaded engagement into the workpiece. Preferably, onlyafter the tip of the screw becomes engaged in the workpiece, does thehead of the screw come into contact with the sleeves. Further, forwardmovement of the screw into the workpiece then draws the head downwardlyto engage the sleeve and to rupture the sleeve by reason of the forwardmovement of the head with the strip retained against movement towardsthe workpiece. The sleeve preferably is configured to have fragilestrips which break on the head passing through the sleeve such that thestrip remains intact as a continuous length. Since the strip is acontinuous length, on advancing the screwstrip with each successivescrew to be driven, it necessarily results that portion of the stripfrom which each screw has been driven are also advanced to exit from thepower screwdriver.

Known power screwdrivers for driving such collated screwstrips includeU.S. Pat. No. 4,146,071 to Mueller et al, issued Mar. 27, 1976, and U.S.Pat. No. 5,186,085 to Monaceli, issued Feb. 16, 1993, the disclosure ofwhich are incorporated herein by reference. Such known powerscrewdrivers include a rotatable and reciprocally moving screwdrivershaft which is turned in rotation by an electric motor. A screwdrivingbit forms a forwardmost portion of the shaft for engaging the head ofeach successive screw as each screw is moved into a driving position,axially aligned under the screwdriver shaft.

An important aspect of such power screwdriver is the manner and accuracywith which the screws are advanced and positioned so as to be properlyaligned axially under the screwdriver shaft for successful initial andcontinued engagement between the bit and the screwdriver head in drivinga screw fully down into a workpiece. In the device of Mueller et al, aguide channel is provided through which the screwstrip is advanced. Theguide channel is sized to receive screws of specific head size andminimum length. The guide channel is formed as an integral part of asliding body which also carries other components of a screw advancemechanism including a feed pawl to engage the screwstrip and therebyadvance successive screws in the screwstrip. The screws are successivelyadvanced into position in alignment with the screwdriver shaft with theheads of the screws being urged into abutment with a stop which is tolocate the screw head. The stop typically defines a radial extent of aboreway through which the shaft and screw head axially move as the screwis driven.

The shaft is axially movable in the boreway in a reciprocal manner toengage the screw and drive it into a workpiece. After each screw isdriven the shaft retracts and a subsequent screw carried on thescrewstrip is advanced sideways into the boreway, engaging the stop soas to be aligned under the shaft.

Known power drivers for collated screws have a slide body which isreciprocally slidable relative a housing in a normal cycle of operation.Known screw advance mechanisms are coupled between the slide body andhousing to translate relative movement of the slide body and housinginto a cyclical cycle of advance of the screwstrips.

Known screw advance mechanisms suffer the disadvantage that they arecomplex and typically involve a number of components. For example, inthe device of Mueller et al, U.S. Pat. No. 4,146,071, the advancemechanism comprises three interrelated lever members together with acamming roller which cams on a camming surface. A primary spring biasesthe slide body to an extended position relative the housing. A secondaryspring biases the lever members to urge the roller into the cammingsurface and the screwstrip towards the fully advanced position. Thesecondary spring has the disadvantage of being relatively strong andrequiring substantial additional forces for operation so as to telescopethe slide body into the housing and overcome the additional frictionalforces developed between the camming roller and the camming surfaces.

Known screwstrip advance mechanisms are unduly complex, expensive tomanufacture, cumbersome, bulky and inconsistent in their features with alightweight tool of minimum size.

SUMMARY OF THE INVENTION

To at least partially overcome these disadvantages of the prior art, thepresent invention provides a screwdriver for driving collated screwsincluding a slide body coupled to a housing for reciprocal displacementin a cycle including a retraction stroke and an extension stroke, alever pivotably mounted to the slide body carries at one end a cam pinreceived in a cam slot in the housing with the other end of the leveradvancing successive screws in the screwstrip, the cam slot having firstand second camming surfaces for selective engagement by the cam pin tovary the relative positioning of the lever to be different for the samepositions of the slide body in the housing in the retraction strokesthan in the extension stroke.

An object of the present invention is to provide a simplifiedarrangement for translating relative positioning of the slide body andthe housing into positioning of the screw advance mechanism, yetpermitting for different positions in an extension stroke versus aretraction stroke.

Another object is to provide in an attachment for driving collatedscrews an enhanced sequencing of relative positioning of the screw to bedriven, the next screw to be driven and the mandrel in cyclical steps ofadvancing and driving each screw.

Accordingly, in one aspect the present invention provides an apparatusfor driving with a power driver a screwstrip comprising threadedfasteners, such as screws or the like, which are joined together in astrip comprising:

a housing;

an elongate driver shaft for operative connection to a power driver forrotation thereby and defining a longitudinal axis;

a slide body coupled to the housing for displacement parallel to theaxis of the driver shaft between an extended position and a retractedposition;

the slide body having a guide channel for said screwstrip transverse tothe axis,

a shuttle carried on the slide body movable relative the slide bodytransverse to the axis towards and away from the axis,

the shuttle carrying pawl means for. engagement with the screwstrip toadvance the screwstrip with movement of the shuttle towards the axis toplace successive of the fasteners into axial alignment with the drivershaft for driving by the driver shaft,

a lever having a first end coupled to the shuttle and a second endcoupled to the housing whereby movement of the slide body axiallyrelative the housing (a) towards the extended position moves the shuttletowards the axis and (b) away from the extended position moves theshuttle away from the axis,

the lever pivotably mounted on the slide body intermediate its first andsecond ends;

the housing having an elongate cam slot having side-by-side first andsecond camming surfaces,

the second end of the lever carrying a cam pin member slidably engagedin the cam slot between the first and second camming surfaces;

the slide body moving relative the housing in a cycle of operation inwhich the slide body moves in a retracting stroke from the extendedposition to the retracted position and then moves in an extending strokefrom the retracted position to the extended position,

in at least some identical relative positions of the slide body andhousing, the pin member engages the first camming surface in theretracting stroke and the second camming surfaces in the extendingstroke such that the lever places the shuttle at different positionsrelative the identical positions of the slide body and housing in aretracting stroke than in an extending stroke.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects and advantages of the present invention will appear fromthe following description taken together with the accompanying drawings,in which:

FIG. 1 is a pictorial view of a power screwdriver in accordance with afirst preferred embodiment of the present invention;

FIG. 2 is an exploded pictorial view of the housing and slide body shownin FIG. 1;

FIG. 3 is a pictorial view of the opposite side of the slide body tothat shown in FIG. 2 but with a screwstrip positioned therein;

FIG. 4 is a schematic partially cross-sectional view of the driverattachment of FIG. 1 in a fully extended position as seen in FIG. 1through a plane passing through the longitudinal axis of the drive shaftand centrally of the screws in the screwstrip;

FIG. 5 is a view identical to FIG. 4 but with the drive attachment in apartially retracted position in driving a screw into a workpiece;

FIG. 6 is an end view of the nose portion of FIG. 2;

FIG. 7 a pictorial view of the nose portion shown in FIG. 2 but modifiedin accordance with a second embodiment of the invention to provide aretractable screw locating plate;

FIG. 8 is a cross-sectional view through section VIII-VIII′ in FIG. 7;

FIG. 9 is a pictorial view of an optional clutch drive shaft inaccordance with another aspect of the invention;

FIG. 10 is a cross-sectional view of the drive shaft of FIG. 9 passingthrough the longitudinal axis in FIG. 9 and with the drive shaft in adisengaged position;

FIG. 11 is a view identical to that of FIG. 10 but with the drive shaftin an engaged position;

FIG. 12 is a schematic pictorial view of a second version of a removablenose portion;

FIG. 13 is a partially cut-away pictorial view of the nose portion ofFIG. 12 from a different perspective;

FIGS. 14, 15, 16 and 17 are similar views of the nose portion of FIG. 12shown with the last screw in a strip in successive positions as it isdriven from the nose portion;

FIG. 18 is a cross-sectional side view of the nose portion of FIG. 14along vertical section 18-18′;

FIG. 19 is a vertical cross-section of the nose portion of FIG. 14 alongvertical cross-section 19-19′;

FIG. 20 is a horizontal cross-section along section line 20-20′ of FIG.19;

FIG. 21 is a vertical cross-section of the nose portion of FIG. 17 alongvertical section line 21-21′;

FIG. 22 is a horizontal cross-section along section line 22-22′ in FIG.21.

FIG. 23 is a schematic pictorial view similar to FIG. 13 but of a thirdversion of a removable nose portion;

FIG. 24 is a pictorial view of a power screwdriver similar to that inFIG. 1 but driving a screwstrip of fixed length having a curvedconfiguration;

FIG. 25 is an exploded pictorial front view similar to FIG. 2 but of asecond embodiment of driver attachment in accordance with thisinvention;

FIG. 26 is a rear view of the components of the driver attachment ofFIG. 25 assembled;

FIGS. 27 and 28 are pictorial views from opposite angles of a driverassembly utilizing the driver attachment of FIG. 25;

FIG. 29 is an exploded pictorial view of a housing and slide bodysimilar to FIG. 2, however, showing another aspect of the presentinvention having a modified camming arrangement with a pin and cam slotto move the advance lever in relation to relative sliding of the slidebody and housing;

FIG. 30 is a pictorial view of the opposite side of the slide body tothat shown in FIG. 29 but with a screwstrip positioned therein;

FIGS. 31 to 41 are side views of the driver attachments of FIGS. 29 and30 showing the attachment in successive positions in a cycle ofoperation, with FIG. 31 showing the attachment in a fully extendedposition and FIG. 38 showing the attachment in the fully retractedposition.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is made to FIG. 1 which shows a complete power screwdriverassembly 10 in accordance with the present invention. The assembly 10comprises a power driver 11 to which a driver attachment 12 is secured.The driver attachment 12 carries a cartridge 9 containing a coil of acollated screwstrip 14 with spaced screws 16 to be successively driven.

Reference is made to FIG. 2 showing an exploded view of major componentsof the driver attachment 12 as housing 18 and a slide body comprising arear portion 22 and a removable nose portion 24. FIGS. 4 and 5 show incross-section the interaction of these components.

As seen in FIG. 4, the rearmost end 26 of the housing 18 has arearwardly directed socket 27 with a longitudinal slot 28 in its sidewall to receive and securely clamp the housing 18 onto the housing 30 ofthe power driver 11 so as to secure the housing 18 of the driverattachment to the housing 30 of the power driver against relativemovement. The power driver 11 has a chuck 32 rotatable in the driverhousing 30 by an electric motor (not shown). The chuck 32 releasablyengages the driver shaft 34 in known manner. The housing 18 is providedwith a lateral flange 36 at its rear end to which a known screwstripcontaining cartridge 9 is secured in a conventional manner.

As seen in FIG. 4, the slide body 20 is slidably received in the housing18 with the driver shaft 34 received in a bore passing through the rearportion 22 and nose portion 24 of the slide body 20. A compressionspring 38 disposed between the housing 18 and the rear portion 22coaxially about the driver shaft 34 biases the slide body away from thehousing 18 from a retracted position towards an extended position. Asshown, the spring 38 is disposed between the housing 18 and the rearportion 22. Slide stops 25, best shown in FIG. 2, are secured to therear portion 22 of the slide body. Two slide stops 25 slide in twolongitudinal slots 40 on each side of the part cylindrical side wall 42of the housing 18 to key the rear portion 22 of the slide body to thehousing 18 against relative rotation and to prevent the slide body beingmoved out of the housing 18 past a fully extended position.

The rear portion 22 comprises a generally cylindrical element 44 with aradially extending flange element 46 on one side. A lever 48 ispivotally mounted to the flange element 46 by bolt 50 for pivoting aboutan axis 51 of bolt 50 normal to a longitudinal axis 52 which passescentrally through the drive shaft 34 and about which the drive shaft isrotatable. Lever 48 has a forward arm 54 extending forwardly to itsfront end 56 and a rear arm 58 extending rearwardly to its rear end 60.A cam follower 62 has its forward end 63 mounted to the rear end 60 ofthe rear arm 58 by a bolt 64 being received in a slot 65 extendinglongitudinally in the rear end of the rear arm 58. The cam follower 62has at its rear end 66 two cam rollers 67 and 68 rotatable on pinsparallel to the axis of bolts 50 and 64.

As seen in FIGS. 2 and 4, the housing 18 carries a camming channel 70 inwhich the cam rollers 67 and 68 are received. The camming channel 70 isdisposed to one side of the driver shaft 34 and extends generallyparallel thereto. The camming channel 70 has opposed camming surfaces 71and 72 at least partially closed by side walls 73 and 74.

The camming channel 70 extends rearwardly beside the socket 27 ofhousing 18 and thus rearwardly past the chuck 32 of the power driver 11to one side thereof. This configuration permits the use of a housing 18which is of a lesser length parallel longitudinal axis 52 for a givenlength of the cam follower 62 and of the lever 48, rearward of bolt 50.

A spring 69 wound about bolt 50 is disposed between the flange element46 and the forward arm 54 of the lever 48 to bias the lever in aclockwise direction as seen in FIG. 4. The effect of spring 69 is tourge the cam roller 67 into engagement with cam surface 71 and to urgecam roller 68 into engagement with cam surface 72.

With relative sliding of the slide body 20 and the housing 18 betweenthe extended and the retracted positions, the cam follower 62 translatesthe relative movement and positioning of the slide body 20 and housing18 into relative pivoting and positioning of the lever 48 about the axis51. The ability of bolt 64 to slide longitudinally in the longitudinalslot 65 provides a lost motion linkage as is known and is advantageoussuch that the relative timing of pivoting of the lever 48 varies ascompared to the relative location of the slide body 20 and housing 18 inmoving towards an extended position as contrasted with moving towards aretracted position.

The nose portion 24 has a generally cylindrical screw guide element orguide tube 75 arranged generally coaxially about longitudinal axis 52and a flange-like screw feed channel element 76 extending radially fromthe guide tube 75.

The guide tube 75 has a cylindrical portion 77 at its rear end with acylindrical exterior surface sized to be closely received, preferably ina friction fit, within a forwardly opening cylindrical bore 78 in theforward end of the rear portion 22. A radially extending key 80 isprovided to extend from the cylindrical portion 77 of the nose portion24 to be received in a correspondingly sized keyway slot 82 in the rearportion 22 as best seen in FIGS. 4 and 7 to secure the nose portion 24to the rear portion 22 against relative pivoting about the longitudinalaxis 52.

The guide tube 75 has a cylindrical bore or guideway 82 extendingaxially through the guide tube with the guideway 82 delineated andbordered by a radially extending cylindrical side wall 83 and open atits forward axial end 84 and at its rearward axial end 85.

The guide tube 75 has a rearward section adjacent its rear end 85 inwhich the side wall 83 extends 360° about the guideway 82. Forward ofthe rearward section, the guide tube has a forward section best seen inFIG. 4 and which has an access opening 86, shown in the drawings asbeing on the right hand side of the guide tube 75. Screw access opening86 is provided to permit the screwstrip 14 including retaining strip 13and screws 16 to move radially inwardly into the guideway 82 from theright as seen in FIG. 4 and 5. Each screw preferably has a head 17 witha diameter marginally smaller than the diameter of the side wall 83. Itfollows that where the head of the screw is to enter the guideway 82,the screw access opening must have circumferential extent of at least180°. Where the shank 208 of the screw is to enter the guideway, thescrew access opening may have a lesser circumferential extent.

In the forward section, the side wall 83 of the guide tube 75 engagesthe radially outermost periphery of the head 17 of the screw 16, toaxially locate the screw head 17 coaxially within the guideway 82 inaxial alignment with the drive shaft 34. In this regard, the side wall83 preferably extends about the screw sufficiently to coaxially locatethe screw head and thus preferably extend about the screw head at least120°, more preferably, at least 150° and most preferably about 180°.

An exit opening 87, shown towards the left hand side of the guide tube75 in FIGS. 4 and 5, is provided of a size to permit the spent plasticstrip 13 from which the screws 16 have been driven to exit from theguideway 82. Forwardly of the exit opening 87, the side wall 83 of theguide tube 75 is shown as extending greater than about 180° about thelongitudinal axis 52 so as to continue to provide a side wall 83 whichcan assist and positively coaxially guiding the head 17 of a screw 16being driven.

The screw feed channel element 76 is best seen in FIGS. 3 and 4 asproviding a channelway 88 which extends radially relative thelongitudinal axis 52 to intersect with the guideway 82 in the guide tube75. In this regard, the channelway 88 opens to the guideway 82 as thescrew access opening 86. The channelway 88 provides a channel of across-section similar to that of the screw access opening 86 from thescrew access opening 86 to a remote entranceway opening 90. Thechannelway 88 is defined between two side walls 91 and 92 joined by atop wall 93. The major side wall 91 is shown as extending from the heads17 of the screws 16 forwardly to at least partially behind the plasticretaining strip 13. The lesser side wall 92 is shown as extending fromthe heads 17 of the screws 16 forwardly to above the plastic strip 13.Stopping the lesser side wall from extending down over the strip 13assists in reducing friction between the strip 13 and the lesser sidewall. The side walls 91 and 92 define the channelway 88 with across-section conforming closely to that of the screwstrip 14 and itsstrip 13 and screws 16 with an enlarged width where the heads of thescrews are located and an enlarged width where the retaining strip 13 isprovided about the screws. The side walls 91 and 92 also have anenlarged funnelling section at the entranceway opening 90 which tapersinwardly to assist in guiding the screwstrip to enter the channelway.

As best seen in FIG. 3, the major side wall 91 is provided on itsexterior back surface with a raceway 94 extending parallel thechannelway 88 and in which a shuttle 96 is captured to be slidabletowards and away from the guide tube 75 between an advanced positionnear the guide tube and a withdrawn position remote from the guide tube.The shuttle 96 has a rear surface 97 in which there is provided arearwardly directed opening 98 adapted to receive the front end 56 ofthe forward arm 54 of lever 48 so as to couple the shuttle 96 to thelever 48 for movement therewith.

Shuttle 96 carries a pawl 99 to engage the screwstrip 14 and withmovement of the shuttle 96 to successively advance the strip one screwat a time. As seen in FIG. 6, the shuttle 96 has a fixed post 100 onwhich the pawl 99 is journalled about an axis parallel the longitudinalaxis 52 about which the driver shaft 34 rotates. The pawl 99 has a strippusher arm 101 which extends through a slot 103 in the major side wall91 to engage and advance the screwstrip. The pawl 99 has a manualrelease arm 102 away from pusher arm 101 and which extends out through aslot 104 in the shuttle 99. A torsional spring is disposed about post100 between pawl 99 and shuttle 96 and urges the pusher arm 101clockwise as seen in FIG. 6. The spring biases the pusher arm 101 intothe screwstrip 14. The engagement of release arm 102 on the right handend of slot 104 limits the pivoting of the pawl 99 clockwise to theposition shown in FIG. 6.

The pusher arm 101 of the pawl 99 has a cam face 107. On the shuttlemoving away from the guide tube 75 towards the withdrawn position, i.e.,to the left in FIG. 6, the cam face 107 will engage the screws 16 and/orthe strip 13 and permit the pusher arm 101 to pivot about post 100against the bias of spring so that the pusher arm 101 may move with theshuttle to the left.

The pusher arm 101 has an engagement face 108 to engage the screws 16and/or strip 13. On the shuttle moving towards the guide tube 75 towardsthe advanced position, i.e., to the right in FIG. 6, the engagement face108 will engage the screws 16 and/or strip 13 and advance the screwstripto the right as seen in FIG. 6 so as to position a screw 16 into theguideway 82 in a position to be driven and to hold the screwstrip 14against movement towards the left. Preferably, as shown in FIG. 4, theengagement face 108 of the pusher arm engages the screw between its head17 and the strip 13 as this has been found advantageous, particularly toavoid misfeeding with a nose portion 24 as shown with engagement of thescrew heads in the channelway 88 and engagement of the spent strip 13′with the support surface 125.

The release arm 102 permits manual withdrawal of the screwstrip 14. Auser may with his finger or thumb manually pivot the release arm 102against the bias of spring so that the pusher arm 101 and its engagementface 108 is moved away from and clear of the screwstrip 14 whereby thescrewstrip may manually be withdrawn as may be useful to clear jams orchange screwstrips.

With the nose portion 24 coupled to the rear portion 22, the lever 48couples to the shuttle 96 with the forward arm 54 of lever 48 receivedin the opening 98 of the shuttle 96. Sliding of the slide body 20 andthe housing 18 in a cycle from an extended position to a retractedposition and then back to an extended position results in reciprocalpivoting of the lever 48 about axis 51 which slides the shuttle 96between the advanced and withdrawn position in its raceway 94 and henceresults in the pawl 99 first retracting from engagement with a firstscrew to be driven to behind the next screw 16 and then advancing thisnext screw into a position to be driven. The

The nose portion 24 is removable from the rear portion 22. The noseportion 24 and rear portion 22 may be coupled together by axiallyinserting the cylindrical portion 77 of the guide tube 75 into the bore78 in the rear portion 22 with the key 80 aligned with the keyway slot82 and with the front end 56 of the forward arm 54 of the lever 48aligned with the opening 98 in the shuttle 96. Thus, the removable noseportion 24 may be coupled to the rear portion 22 merely by axiallyaligning the nose portion and the rear portion and moving the twoelements together in a direction parallel the longitudinal axis 52.

With the nose portion 24 held on the rear portion 22 by a friction fit,the nose portion 24 can manually be removed by a user merely by themanual application of force. The nose portion 24 is removable from therear portion 22 without disassembly or uncoupling of any of theremainder of the screwdriver assembly 10. Thus, the nose portion 24 isremovable without uncoupling of the rear portion 22 relative any of thehousing 18, spring 38, power driver 11, driver shaft 34 or the screwfeed activation mechanism comprising amongst other things the lever 48and cam follower 62 and without uncoupling of the cam follower 62 incamming channel 70 of the housing 18.

The nose portion 24 carries the guide tube 75 with its screw locatingguideway 82, the screw feed channel element 76 with its channelway 88,and screw feed advance mechanism with the reciprocating shuttle 96 andpawl 99 to advance the screwstrip 14 via the channelway 88 into theguideway 82. Each of the guideway 82, channelway 88 and shuttle 96 arepreferably customized for screwstrips and screws or other fasteners of acorresponding size. In this context, size includes shape, head diameter,shaft diameter, retaining strip configuration, length, spacing of screwsalong the retaining strip and the presence or absence of washes amongstother things. Different nose portions 24 are to be configured fordifferent screwstrips and screws. The different nose portions 24 areeach compatible with the same rear portion 22 and are readilyexchangeable so as to permit the driver attachment to be readily adaptedto drive different screwstrips and screws.

Many changes can be made to the physical arrangement of the nose portion24 to accommodate different screws and fasteners. For example, thecross-sectional shape of the channelway 88 can be changed as can thediameter of the guideway 82. The length of the sidewalls 91 and 92 aboutthe channelway 88 can be varied to accommodate different size screwswhich may require greater or lesser engagement.

To adjust for different spacing between screws in different screwstrips,the stroke of the shuttle 96 in reciprocating back and forth can beshortened or lengthened by varying the distance from the axis 51 of thelever 48 to where the shuttle 96 engages the forward arm 54 of the lever48. For example, placing the same shuttle 96 in a raceway 94 spacedfurther from the axis 51 will increase the length of the stroke of theshuttle 96 for the same arc of pivoting of lever 48. Similarly, usingthe same shuttle 96 in the same raceway 94 but having the opening 98 inthe shuttle 96 to engage the lever 48 farther from the axis 51 will alsoincrease the length of the stroke of the shuttle 96 for the same arc ofpivoting of lever 48.

In contrast with the removable nose portion 24 which is intended to beprovided in many different replaceable configurations, the remainder ofthe driver attachment is preferably of a constant unchangedconfiguration. In this regard, the remainder of the driver attachmentmay be characterized by the housing 18, rear portion 22 of the slidebody 20, drive shaft 34 and spring 38 together with a screw feedactivation mechanism comprising the lever 48 cam follower 62 interactingbetween the rear portion 22 and the housing 18. This screw feedactivation mechanism is activated by relative movement of the housing 18and rear portion 22 and serves to engage and move the screw feed advancemechanism comprising the shuttle 96 and pawl 99 carried on the noseportion 24.

The construction of the housing 18 and slide body 20 provide for acompact driver attachment.

The housing 18 has a part cylindrical portion formed by side wall 301.

The slide body 20 as best seen in FIG. 3 comprising the rear portion 22and nose portion 24, has a part cylindrical portion of a uniform radiussized to be marginally smaller than the side wall 301 of the housing 18.The side wall 301 extends circumferentially about the part cylindricalportion of the slide body 20 to retain the slide body 20 therein.

The housing has a flange portion 302 which extends radially from oneside of the part cylindrical portion and is adapted to house theradially extending flange 46 of the rear portion 22 and the screw feedactivation mechanism comprising the camming channel 70 interacting withthe lever 48 and cam follower 62. The flange portion 302 is open at itsfront end and side to permit the screw feed channel element 76 to slideinto and out of the housing 18. Concentrically located about the driveshaft 34 is the spring 38, the part cylindrical portions of the slidebody 20, and the part cylindrical portions of the housing 18.

The driver attachment is provided with an adjustable depth stopmechanism which can be used to adjust the fully retracted position, thatis, the extent to which the slide body 20 may slide into the housing 18.The adjustable depth stop mechanism is best seen in FIGS. 2 and 3 ascomprising an elongate rod 110 slidably received in an elongate openended bore 111 provided in the side wall 42 of the housing 18 andextending parallel to longitudinal axis 52.

A depth setting cam member 114 is secured to the housing 18 for rotationabout a pin 116 parallel the longitudinal axis 52. The cam member 114has a cam surface 115 which varies in depth, parallel the longitudinalaxis 52, circumferentially about the cam member 114. A portion of thecam surface 115 is always axially in line with the rod 110. A spring 113biases the rod 110 rearwardly such that the rear end 117 of the rodengages the cam surface 115. The spring 112 is disposed between thehousing and a pin 113 on the rod. By rotation of the cam member 114, theextent to which the rod 110 may slide rearwardly is adjusted.

The rod 110 has a front end 118 which extends forwardly from bore 111for engagement with rearwardly directed annular stop surface 119provided on the nose portion 24 of the slide body. The slide body 20 isprevented from further sliding into the housing 18 when the front end118 of the rod 110 engages the stop surface 119. The extent the slidebody 20 may slide into the housing 18 is determined by the length of therod 110 and the depth of the cam member 114 axially in line with therod. The cam member 114 is preferably provided with a ratchet-likearrangement to have the cam member 114 remain at any selected positionbiassed against movement from the selected position and with circularindents or depressions in the cam surface 115 to assist in positiveengagement by the rear end 117 of the rod. The cam member 114 isaccessible by a user yet is provided to be out the way and not interferewith use of the driver attachment. The depth stop mechanism controls theextent to which screws are driven into a workpiece and thus controls theextent of countersinking. As the depth stop mechanism controls thedistance from the workpiece the bit 122 must stop, a given countersinksetting will be effective even if strips are switched to use screws of adifferent length. Adjustment is not required merely because differentlength screws are to be used.

The nose portion 24 may be customized for use in respect of differentsize screws by having the location of the stop surface 119 suitablyprovided axially on the nose portion 24 as may be advantageous for useof different size screws.

The driver shaft 34 is shown in FIGS. 4 and 5 as carrying a split washer120 engaged in an annular groove near its rear end 121 to assist inretaining the rear end of the driver shaft in the socket 27 of thehousing 18. The driver shaft 34 is provided with a removable bit 122 atits forward end which bit can readily be removed for replacement byanother bit as for different size screws. Such bits include sockets andthe like in any replacement bits will preferably be of an outsidediameter complementary to the inside diameter of the guideway 82 in acorresponding replacement nose portion adapted for use with acorresponding sized screws. To accommodate bits of increased diameterover the bit shown in FIGS. 4 and 5, the guideway 82 of the guide tube75 may be provided with an increased radius, at least commencing at thelocation where the bit may have an enlarged diameter and extendingforwardly therefrom. The guideway 82 in the guide tubes 75 may thus havea step configuration with the sidewall 83 being of a reduced diameterwhere the driver shaft 34 enters the rear of the guide tube 75 and theside wall 83 may then increase to an enlarged diameter forwardly toaccommodate an enlarged bit such as a socket.

The rear portion 22 is shown in FIGS. 4 and 5 as having a radiallyinwardly extending annular flange 19 which provides the end of theforwardly opening bore 78 as well as the end of a rearwardly openingbore 79 within which the spring 38 is received. The annular flange 19has an opening therethrough of a diameter slightly larger than thediameter of the driver shaft 34 so as to assist in journalling thedriver shaft therein. The opening through the annular flange 19 mayhowever be increased so as to facilitate the use of driver shafts 34having enlarged diameters as well as a driver shafts 34 having reduceddiameters.

Insofar as the driver shaft 34 has a removable bit 122, it is preferredthat as shown, when the driver attachment 12 is in the fully extendedposition and the nose portion 24 is removed, the bit 122 be readilyaccessible for removal and replacement. In this regard, it is preferredthat the nose portion 124 have a guideway 82 of a minimum diameterthroughout its length at least equal to the diameter of the bit 122 suchthat the nose portion 24 may be removed from the rear portion 22 withoutthe need to remove the bit 122 as may otherwise be the case in the eventthe guideway 82 may have a stepped configuration.

Operation of the driver attachment is now explained with particularreference to FIGS. 4 and 5. As seen in FIG. 4, the screws 16 to bedriven are collated to be held parallel and spaced from each other bythe plastic retaining strip 13.

In operation, a screwstrip 14 containing a number of screws 16 collatedin the plastic retaining strip 13 is inserted into the channelway 88with the first screw to be driven received within the guideway 82. Todrive the first screw into the workpiece 124, the power driver 11 isactivated to rotate the driver shaft 34. The driver shaft 34 and its bit122, while they are rotated, are reciprocally movable in the guideway 82towards and away from the workpiece 124. In a driving stroke, manualpressure of the user pushes the housing 18 towards the workpiece 124.With initial manual pressure, the forward end 25 of the nose portionengages the workpiece 124 to compress spring 38 so as to move slide body20 relative the housing 18 into the housing 18 from an extended positionshown in FIG. 4 to a retracted position. On release of this manualpressure, in a return stroke, the compressed spring 38 moves the slidebody 20 back to the extended position thereby moving the housing 18 andthe driver shaft 34 away from the workpiece.

In a driving stroke, as the driver shaft 34 is axially moved towards theworkpiece, the bit 122 engages the screw head 17 to rotate the firstscrew to be driven. As is known, the plastic strip 13 is formed torelease the screw 16 as the screw 16 advances forwardly rotated by thedriver shaft 34. Preferably, the screw tip will engage in a workpiecebefore the head of the screw engages the strip such that engagement ofthe screw in the workpiece will assist in drawing the screw head throughthe strip to break the fragible straps, however, this is not necessaryand a screw may merely, by pressure from the drive shaft, be releasedbefore the screw engages the workpiece. Preferably, on release of thescrew 16, the plastic strip 13 deflects away from the screw 16 outwardlyso as to not interfere with the screw 16 in its movement into theworkplace. After the screw 16 is driven into the workpiece 124, thedriver shaft 34 axially moves away from the workpiece under the force ofthe spring 38 and a successive screw 16 is moved via the screw feedadvance mechanism from the channelway 88 through the access opening 86into the guideway 82 and into the axial alignment in the guideway withthe driver shaft 34.

The screw 16 to be driven is held in position in axial alignment withthe driver shaft 34 with its screw head 17 abutting the side wall 83 inthe guideway 82. As a screw 16 to be driven is moved into thecylindrical guideway 82, a leading portion of the strip 13′ from whichscrews have previously been driven extends outwardly from the guideway83 through the exit opening 87 permitting substantially unhinderedadvance of the screwstrip 14.

To assist in location of a screw to be driven within the guide tube 75,in the preferred embodiment the exit opening 87 is provided with arearwardly facing locating surfaced 125 adapted to engage and support aforward surface 222 of the strip 13. Thus, on the bit 122 engaging thehead of the screw and urging the screw forwardly, the screw may beaxially located within the guide tube 75 by reason not only of the headof the screw engaging the side wall 83 of the guideway but also with theforward surface 222 of the strip 13 engaging the locating surface 125 ofthe exit opening 87. In this regard, it is advantageous that the forwardsurface 222 of the retaining strip 13 be accurately formed having regardto the relative location of the screws 16 and particularly the locationof the their heads 17. The forward surface 222 of the strip 13 may becomplementary formed to the locating surface 125 and if desired indexingnotches or the like may be provided in the forward surface 222 of thestrip 13 to engage with complementary notches or indents on the locatingsurface 125 of the entranceway to assist in indexing location of thestrip 13 relative the locating surface and enhance the location therebyof the screw 16 within the guide tube 75.

Reference is now made to FIGS. 7 and 8 which show an alternateembodiment of a removable nose portion which provides another mechanismto locate each successively advanced screw axially aligned with thedriver shaft 34. The alternate embodiment includes a retractable footplate similar to that taught in U.S. Pat. No. 4,146,071 to Mueller etal. The foot plate 128 is provided to engage and fix the position of ascrew adjacent the screw which is to be driven. As seen, the modifiednose portion is provided with a slot 129 which extends rearwardlyparallel longitudinal axis 52. The foot plate 128 has a general L-shapewith a slide portion 130 axially slidably received within the slot 129to slide therein in a direction parallel longitudinal axis 52. A spring131 biases the foot plate 128 out of the slot 129 and while not shown, asuitable stop mechanism is provided to limit the foot plate 128 toextend from the slot 129 to a maximum distance.

The foot plate 128 has a foot portion 132 which extends normal to thelongitudinal axis 52 and provides in a rearwardly facing surface 133 aconical recess 134. This recess 134 is located to be axially in linewith the tip 15 of a “next” screw 16 in the screwstrip 14 adjacent thescrew 16 to be driven.

In use of a driver attachment with a modified nose portion 24 as shownin FIGS. 7 and 8, the foot plate 128 is the first element of theattachment to engage the workpiece. On engaging the workpiece, the footplate 128 slides rearwardly into the slit 129 and thus retracts into thenose portion 24. The foot portion 132 in moving rearwardly engages thetip 15 of the “next” screw 16 next to the screw 16 to be driven andaccurately locates the tip 15 within the conical recess 134. The footportion 132 applies a force to such next screw pushing the screwrearwardly so that the head 17 of the screw bears on the flat top wall93 in the channelway 88. By reason of such next screw being firmlyclamped between the foot plate 128 and the top wall 93 of thechannelway, the screwstrip 14 is effectively locked into position andthereby assists in positioning the screw 16 which is to be drivenaxially aligned with the longitudinal axis 52. It is to be appreciatedthat different removable nose portions 24 may be provided with differentfoot plates 128 having appropriate relative location of the foot portion132 and its conical recess having regard to the length of the screw andto the spacing between the screws along the retaining strip 13. In knownmanner, the foot plate 128 may be provided to be adjustably located onthe nose portion 24.

FIGS. 7 and 8 show an embodiment of the nose portion 24 utilizing incombination three different mechanisms whereby a screw to be drivenadvanced through the screw guide channel mechanism is to be locatedaxially in alignment with the driver shaft 34. The three mechanisms arethe engagement of the screw head with the side wall 83, the engagementof the spent strip 13′ on the locating surface 125 of the exit opening87, and the clamping of the next to be driven screw by the foot plate128. Only one or more of these mechanisms need be provided particularlyinsofar as the channelway 88 may be precisely configured for specificsized screws 16 and screwstrips 14 and provide by itself generallyincreased support and location of the screwstrip 14 without restrictingfree sliding of the screwstrip and its screws therethrough. With animproved correspondence in sizing between the screwstrip 14 and thechannelway 88 and the radial extent of the channelway effectivelylocating the screwstrip and its screws in a plane intersecting thelongitudinal axis 52, a simple guide mechanism may be provided focussingprincipally on constraining the screwstrip 14 or its screw againstmovement radially relative the channelway 88.

In the embodiment of the nose portion 24 shown in FIGS. 1 to 6, on thebit 122 engaging the head 17 of the screw 16 and urging it forwardly inthe guideway 82, the strip 13 is preferably held against movementforwardly firstly by the forward surface 222 of the strip engaginglocating surface 125 and, secondly, by the under surfaces of the heads17 of screws in the channelway 88 engaging on the rearwardly directedshoulders provided on each of the side walls 91 and 92 where theenlarged width cross-section of the channelway 88 accommodating the headof the screws reduces in width as seen in FIG. 3. Together with thelocation of the head 17 of a screw 16 coaxially in the guideway, thescrew 16 to be driven is located axially aligned with the driver shaftwithout any moving parts other than the advance shuttle 96.

The driver attachment 12 disclosed may be provided for differentapplications. In a preferred application, the driver may be used forhigh volume heavy load demands as, for example, as in building houses toapply sub-flooring and drywall. For such a configuration, it ispreferred that with the power driver 11 comprising a typical screw gunwhich inherently incorporates a friction clutch and thus to be extentthat a screw is fully driven into a workpiece, the clutch will, on theforces require to drive the screw becoming excessive, slip such that thebit will not be forced to rotate an engagement with the screw head andthus increase the life of the bit.

Reference is made to FIGS. 29 and 30 which show a driver apparatusidentical to that of FIGS. 1 to 6 but for the following modifications.Firstly, the rear arm 58 of the lever 48 has been modified to provide acam pin 502 near its rear end 504, thus eliminating the slot 65 and thecam follower 62 with its cam rollers 67 and 68. Secondly, a cam slot 506has been provided in the side wall 302 of the housing 18.

The cam slot 506 has a first camming surface 508 and a second cammingsurface 510 spaced therefrom and presenting different profiles as bestseen in side view in FIG. 31. The cam pin 502 is received in cam slot506 between the first and second camming surfaces 508 and 510 forengagement of each under different conditions of operation. Spring 69about bolt 50, as shown in FIG. 4, biases the lever 48 in a clockwisedirection as seen in FIG. 30 and thus biases the lever to pivot in adirection which moves the shuttle 96 towards the axis 52 of the guidetube and biases the cam pin 502 towards the first camming surface 508.

In operation of the driver attachment, the slide body 20 moves relativethe housing 18 in a cycle of operation in which the slide body moves ina retracting stroke from the extended position to the retracted positionand then moves in an extending stroke from the retracted position to theextended position. Whether in any position in a cycle the cam pin 502will engage either the first camming surface 508 or the second cammingsurface 510 will depend on a number of factors. Most significant ofthese factors involve the resistance to movement of the shuttle 96 ineither direction as compared to the strength of the spring 69 tending tomove the shuttle 96 towards axis 52. Under conditions in which the biasof the spring 69 is dominant over resistance to movement of the shuttle96, then the bias of the spring will place the cam pin 502 intoengagement with the first camming surface 508 with relative motion ofthe lever 48 and therefore the shuttle 96 relative the position of theslide body 20 in the housing 18 to be dictated by the profile of thefirst camming surface 508. Under conditions where the resistance tomovement of the shuttle is greater than the force of the spring 96, thenthe cam pin 502 will either engage the first camming surface 508 or thesecond camming surface 510 depending on the direction of such resistanceand whether the slide body is in the retracting stroke or the extendingstroke. For example, in an extension stroke when the shuttle 96 isengaging and advancing the next screw to be driven and the resistanceoffered to advance by the screwstrip may be greater than the force ofthe spring 69, then the cam pin 502 will engage on the second cammingsurface 510.

In the preferred embodiment shown, as best seen in FIG. 31, the firstcamming surface 508 has a first portion 514, a second portion 516 and athird portion 518. The first portion 514 and the second portion 518 aresubstantially parallel the driver shaft axis 52. Second portion 516extends at an angle rearwardly and towards axis 52.

The second camming surface 510 has a first portion 520 which extendsangling forwardly and away from axis 52 and a second portion 522 whichis substantially parallel the axis 52.

The third portion 518 of the first camming surface 508 and the secondportion 522 of the second camming surface 510 are parallel and disposeda distance apart only marginally greater than the diameter of cam pin502 so as to locate the cam pin 506 therein in substantially the sameposition whether the cam pin 502 rides on first camming surface 508 orsecond camming surface 510.

The cam slot 506 has a front end 512 where the first portions 514 of thefirst camming surface 508 merges with the first protion 520 of thesecond camming surface 510. In the front end 512, the width of the camslot 506 is also only marginally greater than the diameter of the campin 502 so as to locate the cam pin 506 therein in substantially thesame position whether the cam pin 502 rides on the first camming surface508 or the second camming surface 510.

The first portion 520 of the second camming surface 510 is spaced fromthe first camming surface 508 and, in particular, its first portion 514and second portion 516 by a distance substantially greater than thediameter of cam pin 502.

Reference is made to FIGS. 31 to 41 which show schematic side views ofthe driver attachment of FIGS. 29 and 30 in successive positions in acycle to drive a screw. In FIGS. 31 to 41, for clarity, none of theslide body 20, nose portion 24 and the strip 13 are shown such that therelative positions of the screw can be seen. In most of FIGS. 31 to 34and 37 to 41, neither the next screw to be driven nor the strip 13 areshown. Only in FIGS. 35 and 36 are the next screw to be driven and thestrip 13 shown.

FIG. 31 shows a view at the start of a cycle with the slide body fullyextended by spring 38. The cam pin 502 is received in the front end 512of cam slot 506 shown in FIG. 4. The shuttle 96 and its pawl 99 hold thescrew to be driven aligned with the driver shaft 34 and its bit 122 byurging the head of the screw into the side wall 83 of the guide tube 75as shown in FIG. 4. The bit 122 is rearward of the screw.

FIG. 32 shows the slide body retracted sufficiently that the bit 122 hasjust become engaged in the head of the screw, although the screw has notyet been advanced. The cam pin 502 has moved rearwardly in cam slot 506sliding up the first portion 514 of the first camming surface 508 of camslot 506. As the first camming surface 508 extends from the front end512 substantially rearwardly parallel the driver shaft axis 52 as thefirst portion 514, the lever 48 does not move from a position holdingthe screw as in FIG. 31.

FIG. 33 shows the slide body further retracted to a point where the bit122 is fully engaged in the head of the screw and the clutch on thepower driver has been engaged and the screw has commenced to rotate. Thecam pin 502 has become engaged on a second portion 516 of the firstcamming surface which angles rearwardly toward the driver shaft and,therefore, with further retraction of the slide body will pivot lever 48to withdrawal shuttle 96.

FIG. 34 shows the slide body further retracted to a point where theshuttle 96 has been withdrawn a sufficient extent that the pawl 99 hasbeen moved out of the axial path of the head of the screw, the bit 122and the driver shaft, by reason of the cam pin 506 riding on the secondportion 516 of the first camming surface 508.

FIG. 35 shows the slide body further retracted to a point where theshuttle 96 has been withdrawn a sufficient extent that its pawl 99 hasbecome engaged behind the next screw to be driven as carried in strip13. The screw which is being driven by the bit 122 has been advancedfrom its position of FIG. 34 into the workpiece, however, the screwbeing driven remains engaged on the strip 13 and has not yet beensevered from the strip 13. The cam pin 506 continues to ride on thefirst camming surface 508.

FIG. 36 shows the slide body further retracted to a position to drivethe screw being driven into a workpiece. FIG. 36 shows that the screwbeing driven has been severed from the strip 13 and the pawl 99 remainson the withdrawal side of the next screw to be driven. The cam pin 506has been moved rearwardly from second angled portion 516 to the thirdportion 518 which extends rearwardly parallel the driver shaft axis 52and, thus, maintains the shuttle 96 in the same relative positionwithdrawn behind the next screw to be driven.

FIG. 37 shows the slide body as fully retracted with the screw drivenfully rearward into a workpiece at the end of the retraction stroke.From the position of FIG. 36 to the position of FIG. 37, the cam pin 502has moved rearwardly along the first camming surface 508 in the straightthird portion 518.

The retraction stroke has been illustrated in a cycle of operation byretraction of the slide body 20 into the housing 18 successively throughthe position of FIGS. 31 to 37. In each of FIGS. 32 to 37, the cam pin502 has been shown as engaged on first camming surface 508 since thebias of spring 69 about lever 48 has been greater than any resistance tomovement of the shuttle 96 towards the advance position.

The extension stroke in a cycle of operation is illustrated by extensionof the slide body successively through the positions of FIGS. 37 to 41and then back to the position of FIG. 31. In the extension stroke, thedriver shaft 34 and its bit 122 is withdrawn rearwardly to locaterearward of a screw to be driven at the same time the screw to be drivenis advanced.

In moving from FIG. 37 to FIG. 38, the cam pin 506 moves along the thirdportion 518 of the first camming surface 508 and the shuttle 96 does notadvance. Once the cam pin 506 starts to engage the second portion 516 ofthe first camming surface 508, the lever 48 commences to move theshuttle 96 towards the advanced position with the pawl 99 first engagingthe screw in the position shown in FIG. 39. In FIG. 39, the head of thescrew is shown spaced to one side radially from the driver shaft 34.

With subsequent advance from the position of FIG. 39 to the position ofFIG. 40, the head of the screw is advanced into contact with the side ofthe driver shaft 34 as seen in FIG. 40. With the head of the screwengaging the driver shaft 34, the resistance forces to advance of theshuttle 96 becomes greater than the bias of the spring 69 about thelever. The location of the head of the screw engaging the driver shaft34 dictates the location of the shuttle 96, lever 48 and cam pin 502.The cam pin 502 is moved off the first camming surface 508 and may floatbetween the first and second camming surfaces. Where there isinterference between the withdrawing driver shaft and the next screw,the distance between the first and second camming surfaces 506 and 508is selected to be at least sufficient that the lever 48 may pivotagainst the bias of spring 69 a sufficient extent that the shuttle 96can assume a position withdrawn the greater of the diameters of thedriver shaft 34 and the bit 122.

The head of the screw is urged into contact with the side of the drivershaft 34 and bit 122 from about the position of FIG. 40 until about theposition of FIG. 41 when the axial end of the bit 122 moves rearwardlyof the head of the screw, at which time the screw is ready to beadvanced into axial alignment with the driver shaft as shown in thefully extended position of FIG. 31.

To advance the screw, the resistance forces to advance met by theshuttle 96 may be greater than the bias of the spring 69 of the lever.In such a condition, as shown in FIG. 41, the cam pin 502 engages thesecond camming surface 510 which can positively urge the lever 48 toadvance the shuttle 96 and screw in advancing to the fully extendedposition of FIG. 31 from the position in FIG. 41.

Having the interference between the screw being advanced and the drivershaft 34 and bit 122 has been found to not be disadvantageous where theforces exerted by spring 69 about the lever 48 are not excessive. Suchinterference could be avoided as by using lost motion devices such asthe slot 65 described with the first embodiment of FIGS. 1 to 6. Theembodiment of FIGS. 29 to 41 has been found to provide advantageousoperation with a more simplified construction.

The embodiment of FIGS. 29 and 30 is particularly advantageous in thatin the final advance of the screwstrip in the end of the extensioncycle, the second camming surface 510 can provide positive advancingforces greater than the force of spring 69 about lever 48. This permitsthis embodiment to utilize a lesser strength spring 69 than othersystems. Using a lesser strength spring reduces the frictional forcesbetween cam pin 502 and the camming surfaces.

The embodiment of FIGS. 29 and 30 is particularly advantageous for usewith a canister 400 containing a coil of a collated screwstrip asillustrated in FIGS. 27 and 28 to drive screws vertically downwardly.With the canister 400 mounted to the slide body 20 and with the screwsto be driven vertically downwardly, the weight of the canister 400 andits screws tend to complement the spring 38 and draw the slide body 20vertically downwardly to the fully extended position. The increasedweight of the canister thus ensures that the cam pin 502 locates fullyin the front end 512 of the cam slot 506 and ensures that the screw tobe driven is fully advanced overcoming any forces resisting advance.

With the preferred embodiments of this invention using but one pawllever, a preferred configuration of the relative timing of pivoting ofthe lever 48 compared to the relative location of the slide body in thehousing 18 is one in which the following aspects (a) and (b) are met,namely:

(a) firstly, the pawl 99 engages the screw to be driven to maintain thescrew in axial alignment with the bit 122 until the bit 122 has engagedin the recess 213 in the screw head for rotational coupling therewith;and

(b) secondly, the pawl 99 sufficiently withdraws itself such that,before the screw being driven detaches itself from the strip 13, thepawl 99 is located engaged on the withdrawal side of the next screw tobe advanced.

Aspect (b) is advantageous to ensure that the screwstrip may not beinadvertently withdrawn or dislodged before the pawl 99 becomes engagedbehind the next screw to be advanced. While the screw being driven isattached to screwstrip, the screwstrip is held by the bit againstremoval by rearward movement. If, however, the screwstrip becomesdetached from the screwstrip before the pawl 99 is behind the next screwto be driven, then at this time, the screwstrip can move in a directionopposite the direction of advance, for example, either to become removedfrom the feed channel element 76 or to be displaced an extent that thepawl cannot engage the next screw to be driven.

To have aspects (a) and (b) permits preferred advantageous operationwith merely a single pawl member utilized to advance each screw, to holdit in place until the bit engages in the screw and then while the screwis held by the bit, to withdrawal to engage behind the next screw to bedriven such that the pawl is engaged behind the next screw when thescrew being driven becomes disengaged from the strip. For example, whereaspect (b) is not satisfied, the difficulty can arise, for example, thatin the movement of the pawl 99 towards the withdrawal position, the pawl99 may engage the strip and itself move the strip in a directionopposite the advance direction. Having a relatively weak spring whichurges the pusher arm 101 of the pawl into the screwstrip can reduce thelikelihood that the pawl 99 may move the strip in a direction oppositethe advance direction. Movement of the strip in a direction opposite theadvance direction can be avoided by the screwstrip and screws beingengaged in the screwdriver in frictional engagement to resistwithdrawal. To some measure, such frictional engagement arises by reasonof the spent screwstrip extending out of the exit opening 87 and thescrew heads, shanks and/or strip frictionally engaging the screw feedchannel element 76 and/or the guide tube 24. However, any such frictionis contrary to a preferred configuration in which the frictional forcesto be overcome by advance of the screwstrip are minimized. Therefore, itis a preferred system with least resistance to advance of the screwstripand with a single pawl that it is most preferred that aspects (a) and(b) being incorporated in a tool.

It is also advantageous that in addition to aspects (a) and (b), thatafter aspect (a) and before aspect (b), an aspect (c) is met whereby thepawl 99 moves toward the withdrawal position sufficiently that the pawl99 is moved out of the path of the head of the screw and the drivershaft 34 and its bit 122 as they advance a screw. This aspect (c) isadvantageous so as to avoid the pawl 99 interfering with the easyadvance of the screw head, bit and mandrel.

Aspects (a), (b) and (c) can be achieved, for example, by the cammingsurfaces moving the lever 48 to hold the shuttle 96 and therefore thepawl 99 at a position either holding or urging the head of the screwinto engagement within the guide tube in axial alignment with the bituntil the bit engages in the recess in the head, rotatably coupling thebit and the screw and preferably driving the screw at least somedistance. However, before the head of the screw moves forwardlysufficiently to engage the pawl 99, if the pawl 99 were not moved fromthe position of aspect (a), the camming surfaces causes the lever 48 topivot moving the shuttle 96 towards the withdrawn position out of theway of the axial path of the head of the screw's bit and mandrel. Thepawl 99 merely needs to be moved towards the withdrawn position suchthat it engages behind the next screw before the screw being drivendisengages from the strip as by the head of the screw rupturing thestrip. However, it is permissible if the pawl 99 moves relativelyquickly compared to the advance of the screw being driven to theposition behind the next screw.

As another fourth aspect to relative timing is the aspect that in theextension stroke a screw being advanced not interfere with withdrawal ofthe driver shaft and its bit. While embodiments can be configured so allinterference is avoided, this is not necessary. Advantageously, whenaspects (a), (b) and (c) are achieved as by minimizing the relative timethat the pawl 99 engages the first screw in satisfying aspect (a), andprompt withdrawal to satisfy aspect (c), this can minimize the relativeextent to which interference can arise between the next screw to bedriven and the bit or mandrel on the extension stroke.

The driver attachment in accordance with the present invention isadaptable for use with conventional power drills which are similar toscrew guns yet do not incorporate a clutch mechanism. The driverattachment may be suitably used with a drill without a clutch preferablywith the user manipulating the drill and driver attachment in use toreduce the likelihood of bit wear by the bit rotating relative the screwhead in a jamming situation. FIGS. 9, 10 and 11 show an optional form ofa driver shaft 34 which provides a simple clutch arrangement as for usewith a power drill which does not have a clutch.

Referring to FIGS. 9 to 11, the modified driver shaft 34 has a rear body136 whose rear end is to be secured in the chuck 32 of a power drill ina normal manner. The driver shaft 34 has a front slide 137 which isaxially slidable relative the rear body 136.

The front slide 137 includes a cylindrical rod 138 of reduced diameterwhich extends forwardly into a forwardly opening cylindrical bore 140 inthe rear body. The bore 140 in the rear body has at its forward end aradially inwardly extending shoulder 141. A split ring 142 carried onthe rod 138 is received in an annular groove 143 about the rod 138. Thesplit ring 142 is provided such that the split ring may be compressedinto the groove 143 to permit the rod 138 to be inserted into the bore140. Once inside the bore 140, the split ring 142 expands outwardly andwill engage with the shoulder 141 so as to retain the rod 138 in thebore 140 against removal. A spring 144 is provided within the bore 140and biases the front slide 137 forwardly away from the rear body 136.

The rear body 136 and front slide 137 have opposed clutch surfaces 147and 148 which when urged together cause the rear body and front slide torotate in unison. However, when the clutch surfaces are disengaged, therear body 136 may rotate without rotation of the front slide 137. Asshown in the drawings, the clutch surfaces comprise complementary teethand slots on the opposed axially directed end surfaces of the rear body136 and the front slide 137. For example, a tooth 145 on rear body 136is adapted to be received within a slot 146 on front slide 137. Whileaxially directed clutch surfaces with teeth may be provided, there are awide variety of known clutch surfaces which may provide tooth and/orfrictional surfaces engagement to transfer rotational forces from therear body 136 to the front slide 137 when the clutch surfaces are urgedaxially into each other. Other preferred surfaces include conicalsurfaces.

In use of a driver attachment with the clutch driver shaft 34 shown inFIGS. 9 to 11, when a screw with initially engaged by the bit of thedriver shaft and a person using the screwdriver assembly pushes down onthe screw, the downward pressure applied by the user compresses thespring 144 and the rear surfaces 148 of the front slide 137 engage thefront surfaces 149 of the rear body 136 in the manner that they arecoupled together for rotation. The coupled position is shown in crosssection in FIG. 11. In this collapsed and engaged position, a screw 16may be driven. On the screw being driven down into a workpiece, thedepth stop mechanism including for example the rod 110 may be utilizedto stop the rear body 136 from moving further towards the workpiece. Therear body 136 stops from further movement towards the workpiece at aposition that the screw is almost fully driven into the workpiece. Atthis point, with further rotation of the driver shaft 34, as the screwis driven by the rotation of the driver shaft 34 further downward intothe workpiece, the screw is drawn away from the rear body 136. Spring144 to some extent assists in ensuring that the bit remains engaged inthe head of the screw. Once the screw head is further advanced into theworkpiece an axial distance greater than the axial height of the teeth145 then the teeth 145 will become disengaged from the slots 146 and therear body 136 will rotate driven by the power drill freely relative tothe front slide 137. It is to be appreciated that by suitably selectingthe depth at which the housing 18 and therefore the rear body 136 isstopped relative the workpiece, the front slide 137 can be permitted todisengage from rotation with the rear body 136 at a position that thescrew becomes screwed into the workpiece a desired extent.

The preferred embodiment illustrated in FIG. 1 shows a screwdriverassembly as including a known cartridge 9 which has a hinge door 150permitting the insertion of a coil of the screwstrip 14 containing, forexample, up to 1000 screws. It is to be appreciated that the use of sucha cartridge is not necessary. For example, rather than provide such acartridge, lengths of the screwstrip could be provided for example, oneor two feet long which could merely be manually fed into the channelway88 when desired.

The driver attachment may be constructed from different materials ofconstruction having regard to characteristics of wear and the intendeduse of the attachment. Preferably, a number of the parts may be moldedfrom nylon or other suitably strong light weight materials. Parts whichare subjected to excessive wear as by engagement with the head of thescrew may be formed from metal or alternatively metal inserts may beprovided within an injection molded plastic or nylon parts. Theprovision of a removable nose portions 24 also has the advantage ofpermitting removable nose portion to be provided with surfaces whichwould bear the greatest loading and wear and which nose portions may beeasily replaced when worn.

The screw feed advance mechanism carried on the nose portion has beenillustrated merely as comprising a reciprocally slidable shuttlecarrying a pawl. Various other screw feed advance mechanisms may beprovided such as those which may use rotary motion to incrementallyadvance the screws. Similarly, the screws feed activation mechanismcomprising the lever 48 and the cam follower have been shown as onepreferred mechanism for activating the screw feed advance mechanism yetprovide for simple uncoupling as between the shuttle 96 and the lever48. Other screw feed activation means may be provided having differentconfigurations of cam followers with or without levers or the like.

In the preferred embodiment, the screwstrip 14 is illustrated as havingscrews extending normal to the longitudinal extension of the strip 13and in this context, the channelway 88 is disposed normal to thelongitudinal axis 52. It is to be appreciated that screws and otherfasteners may be collated on a screwstrip in parallel spaced relation,however, at an angle to the longitudinal axis of the retaining strip inwhich case the channelway 88 would be suitably angled relative thelongitudinal axis so as to locate and dispose each successive screwparallel to the longitudinal axis 52 of the driver shaft.

A preferred collated screwstrip 14 for use in accordance with thepresent invention is as illustrated in the drawings and particularlyFIG. 3 and are substantially in accordance with Canadian Pat. No.1,054,982. The screwstrip 14 comprises a retaining strip 13 and aplurality of screws 16. The retaining strip 13 comprises an elongatethin band formed of a plurality of identical sleeves interconnected bylands 106. A screw 16 is received within each sleeve. Each screws 16 hasa head 17, a shank 208 carrying external threads 214 and a tip 15. Asshown, the external threads extend from below the head 17 to the tip 15.

Each screw is substantially symmetrical about a central longitudinalaxis 212. The head 17 has in its top surface a recess 213 for engagementby the screwdriver bit.

Each screw is received with its threaded shank 208 engaged within asleeve. In forming the sleeves about the screw, as in the manner forexample described in Canadian Pat. No. 1,040,600, the exterior surfacesof the sleeves come to be formed with complementary threaded portionswhich engage the external thread 214 of the screw 16. Each sleeve has areduced portion between the lands 206 on one first side of the strip 13.This reduced strength portion is shown where the strip extends abouteach screw merely as a thin strap-like portion or strap 220.

The strip 13 holds the screw 16 in parallel spaced relation a uniformdistance apart. The strip 13 has a forward surface 222 and a rearsurface 223. The lands 106 extend both between adjacent screws 16, thatis, horizontally as seen in FIG. 3, and axially of the screws 16, thatis, in the direction of the longitudinal axes 212 of the screws. Thus,the lands comprise webs of plastic material provided over an areaextending between sleeves holding the screws and between the forwardsurface 222 and the rear surface 223. A land 206 effectively is disposedabout a plane which is parallel to a plane in which the axes 212 of allthe screws lies. Thus, the lands 206 comprise a web which is disposedsubstantially vertically compared to the vertically oriented screws asshown in the figures. The lands 206 and the sleeves, in effect, aredisposed as continuous, vertically disposed strip 13 along the rear ofthe screws 16, that is, as a strip 13 which is substantially disposedabout a plane which is parallel to a plane containing the axes of allscrews.

A preferred feature of the screwstrip 14 is that it may bend to assume acoil-like configuration due to flexibility of the lands 206, such that,for example, the screwstrip could be disposed with the heads of thescrews disposed into a helical coil, that is, the plane in which all theaxes 212 of the screws lie may assume a coiled, helical configuration toclosely pack the screws for use. Having the lands 206 and sleeves as avertically extending web lying in the plane parallel that in which theaxes 212 permits such coiling.

The invention is not limited to use of the collated screwstripsillustrated. Many other forms of screwstrips may be used such as thoseillustrated in U.S. Pat. Nos. 3,910,324 to Nasiatka; 5,083,483 toTakaji; 4,019,631 to Lejdegard et al and 4,018,254 to DeCaro.

Reference is now made to FIGS. 12 to 22 illustrating a second embodimentof a removable nose portion 24 which is adapted for substitution withthe nose portion 24 illustrated in FIGS. 1 to 6. Throughout FIGS. 12 to22, similar reference numbers are used to refer to similar elements inFIGS. 1 to 11. For simplicity, the nose portion 24 shown in FIGS. 12 to22 is shown merely in the context of the nose portion and/or with ascrewstrip 14 including retaining strip 13 and screws 16. Other elementssuch as the shuttle 96, the shuttle pawl 99, the lever 48, the driveshaft 24, the bit 122 and the workpiece 124 are not shown for thepurposes of simplicity. However, operation and interaction of variousparts is substantially the same.

The nose portion 24 of FIGS. 12 to 21 is identical to the nose portion24 of FIGS. 1 to 6 other than in the configuration of a passageway forthe screwstrip radially through the guide tube 75 from the screw accessopening 86 to the exit opening 87.

In FIGS. 1 to 6, the guide tube 75 has an outboard side which iscompletely cut away between the screw access opening 86 and the exitopening 87. In FIGS. 12 to 22, the guide tube 75 is not completely cutaway on its outboard side but rather has a continuous portion 382 of itsouter wall which separates the screw access opening 86 from the exitopening 87 on the outboard side of the guide tube 75. As used herein,the outboard side is the side to which the strip 13 is deflected when ascrew 16 is separated from the screwstrip 14.

To accommodate deflection of the strip 13 away from a screw 16 towardsthe outboard side, the passageway which extends from the screw accessopening or entranceway 86 to the exit opening or exitway 87 is providedon its outboard side with a lateral strip receiving slotway 304 cut toextend to the outboard side from the cylindrical guideway 82. Theslotway 304, as best seen in FIGS. 18, 19 and 20, is bounded on theoutboard side by side surface 306, at its forward end by ramped surface308 and forward surface 125, and at its rear end by rear surface 312.FIG. 20 shows the side wall 83 of the guideway 82 and with the sidesurface 306 of the slotway 304 spaced towards the ouboard side by thewidth of the ramped surface 308.

The access opening 86 forms an entranceway for the screwstrip 14generally radially into the guideway 82 on one side. The exit opening 87forms an exitway for portions of the strip 13 from which screws 16 havebeen driven, such portions being referred to as the spent strip 13′.

The exit openings or exitway 87 is shown as adapted to encircle thespent strip 13′ with the exitway 87 bordered by rearwardly directedforward surface 125, forwardly directed rear surface 312, inboard sidesurface 314 and outboard side surface 316.

As seen in FIGS. 12 and 13, ramped surface 308 is an axially rearwardlydirected surface which angles forwardly from the forward suface 125towards the entranceway. As seen in FIG. 19, the ramped surface 308 alsoangles forwardly with increasing distance from the axis of the guideway82.

The ramped surface 308 extends forwardly from forward surface 125 atjuncture 218, with the ramped surface following the curvature of theside wall 83 as a ledge of constant width forming a curved sidewallportion 320 merging tangentially into side surface 306.

FIGS. 18, 19 and 20 illustrate the nose protion 24 with a screw 16coaxially disposed within guideway 82 ready to be driven by thescrewdriver bit. FIG. 18 is a cross-section through the screw feedchannel element 76 and shows head 17 of the screw as positioned when thescrew 16 has extended from the channelway 88, through the entranceway 86and into the guideway 82. FIG. 18 also shows clearly how, in respect ofscrews in the channelway 88, the under surfaces of the head 17 are to beengaged on rearwardly directed shoulders 198. FIG. 19 is a cross-sectionthrough the axis of the guideway 82 and shows the guideway 82 having aninner diameter marginally greater than the diameter of the head 17 ofthe screw 16 to be driven therein and with the side wall 83 aboutportions of the guideway 82 adapted to engage the head 17 of the screw16 and assist in coaxially locating the screw 16 in the guideway. Asseen in FIGS. 18 and 19, the forward surface 222 of strip 13 engages theforward surface 125 of the exitway 87.

FIGS. 14, 15, 16 and 17 illustrate successive positions the screwstrip14 assumes in driving the last screw 16 from the strip 13. FIG. 14 showsthe position the last screw assumes when advanced into the guideway 82by the shuttle 9t (not shown). The screw 16 of FIG. 14 is subsequentlyengaged by the bit 122 of the driver shaft 34 (not shown) to be rotatedand pushed forwardly, whereby the screw 16 rotates within the strip 13toward assuming the position shown in FIG. 15 with the head 17 of thescrew 16 near to engaging the strip 13. With continued downward movementof the screw from the position of FIG. 15, the underside of the head 17exerts downward pressure on the strip 13, with the strip 13 to pivotabout the radially inner edge of the forward surface 125 such that thestrip 13 comes to have its terminal end 322 drawn downwardly with thestrip to assume the angled orientation as shown in FIG. 16.

The extent to which the strip may pivot about the radially inner edge ofthe forward surface 125 may be limited by the engagement of the rearsurface 223 of the strip with the rear surface 312 of the exitway 87.The ramped surface 308 preferably is selected to angle forwardly fromthe forward surface 125 such that the ramped surface 308 is below,preferably only marginally below, the forward surface 222 of the strip13 and disposed at substantially the same angle as the forward surface222 of the strip 13.

In FIG. 16, the screw head 17 urges the strip 13 downwardly into theangled configuration shown with the straps 220 continuing to extendabout the shaft of the screw but becoming tensioned and/or stretched.With further driving of the screw 16 forwardly, with the strip 13 beingretained in the angled position against further forward movement, theforward movement of the head 17 breaks the straps 220 and the head 17pushes the strip 13 laterally to the outboard side in the head 17passing forwardly in the guideway 82 past the strip 13. As seen in FIG.21, the strip 13 is located outboard of the guideway 82 and screw 16 inthe slotway with head 17 of the screw free to pass forwardly therepastin the guideway.

FIG. 22 is a top cross-sectional view of FIG. 21. FIG. 22 shows thestrip 13 as deflected to the outboard side into the slotway. FIG. 22also shows the strip 13 as having its terminal end 322 located towardsthe outboard side compared to the leading end 324 of the spent strip13′. The spent strip 13′ can adopt various positions where it exits theexitway 87. The entire strip 13′ can assume a more outboard position aswith the strip's outboard surfaces assuming the position of the dottedline 326 in FIG. 22. The entire strip 13′ can assume a position in whichits leading end 324 extends more inboard, as with the strip′ s outboardsurfaces, assuming the position of the dotted line 328 in FIG. 22, withthe spent strip 13′ to extend diagonally through the exitway 87.

With the inner edge 330 of forward surface 125 curving rearwardly asseen in FIG. 22, engagement between the inner edge 330 and the forwardsurface 222 of the strip tends to pivot the strip to move its terminalend 322 to the outboard side which is advantageous to assist in urgingthe strip 13 into the slotway.

As best seen in FIG. 21, the ramped surface 308 angles forwardly withincreased radius from the axis of the guideway. This assists inengagement between the ramped surface 308 and the forward surface 222 ofthe strip tending to urge the strip 13, or at least the strip's forwardsurface 222, sideways towards the outboard side and away from the screw16 as is advantageous to reduce the likelihood of jamming of the stripunder the head 17 of the screw as between the head 17 and the side wall83.

FIG. 23 shows a third embodiment of a nose portion 24 identical to thenose portion of FIG. 13 but in which the forward surface 125 towards theoutboard side angles forwardly as an angled surface portion 332initially at an angle similar to that of ramped surface 308, thenmerging into a surface portion 334 forward of surface 125.

On the strip 13 being drawn downwardly into the angled configuration asshown in FIG. 16, the angled surface portion 332 and the more forwardsurface portion 334 assist in urging the strip 13 towards the outboardside and into the slotway. The rear surface 312 of the exitway 87 couldalso be configured such that when the strip 13 is angled upwardly, theengagement between the rear surface 232 of the strip 13 and the rearsurface 312 may urge the strip 13 towards the outboard side. FIG. 22shows in dotted lines as 313 an alternate location of rear surface 312which angles rearwardly toward the outboard side.

In FIGS. 14 to 22, the screwstrip 14 has been shown in a preferred formfor screwstrips which are to comprise discrete length segments. Thestrip, as seen in FIGS. 12 and 20, has lands 106 of relatively constantcross-section throughout the length of the strip, with an enlargedflange 107 extending along the outboard side of the strip. Thisstructure and particularly the enlarged flange 107 assists in making thestrip self-supporting, that is, so that a segment will support theweight of the screws against bending. Flange 107 extends in the axialdirection of the screw at least half the height of the lands. The strip13 has been shown with a terminal end 322 which typically would extendfrom the last screw, about one half the distance between screws.

The strip 13 typically would be of a length of at least six inches andmay be very long in the case of a coiled screwstrip. The leading end 324is shown at a location where the strip 13 has ceased to be drawn in thedrawings.

The nose portion 24 is shown as removable for use in an assembly asillustrated. It is to be appreciated that the particular features of theexitway, entranceway and guideway specifically disclosed to assist indriving the last screw in a strip could be used in other guide tubessuch as those which are not removable and which may or may not have anassociated channelway.

The driver attachment 12 in accordance with this invention and the noseportion 24 described herein are particularly adapted for drivingscrewstrips 14 in the form of short segments, preferably in the range ofabout six to eighteen inches in length. One preferred length is abouttwelve inches so as to hold, for example, about 32 screws of, forexample, drywall screws or wood screws. To provide each segment withsufficient rigidity to be self-supporting, it is preferred to providethe strip 13 to have increased dimensions normal the axis of the screwon the outboard side of the screws as, for example, with the lands 206extending as a continuous web along the outboard side of the screws asseen in FIG. 20. Reinforcing rib or flange 107 may be provided along theentire length of the lands 206 as seen in FIGS. 19 and 20. Such areinforcing flange 107 or rib is of assistance in maintaining the axisof the screws in the same plane against coiling. The enlarged slotway inthe nose portion of FIG. 12 is readily adapted to accommodate stripswith such lands 206 and ribs 336 of increased width.

When, as shown in FIG. 14, the last screw 16 in a strip is located inthe guideway, the fact that the exitway 86 encloses the spent strip 13′prevents the strip from rotating about the axis of the guideway to anorientation in which the screw 16 might be able to drop out of theguideway or the screw when driven is increasingly likely to jam. Thespent strip 13′ may extend from the exitway 87 at various angles limitedonly by the location of the side surfaces 314 and 316. Surface 314extends radially away from the guideway and towards the inboard side.

The configuration of FIGS. 12 to 23 is advantageous to better ensurethat the last screw 16 in any screwstrip 14 is driven and to generallyassist in reducing the likelihood of any screw 16 being driven becomingjammed in the guideway with the strip 13.

Preferred strip segments for use with the drive attachment in accordancewith this invention are as shown in FIG. 12, segments of discrete lengthin which the axis of all strips lie in the same flat plane and in whichthe heads 17 of the screws are all located in a straight line.

FIG. 24 schematically shows a driver assembly similar to that in FIG. 1but adapted to drive a screwstrip of a segment 340 of discrete length,but which is curved in the sense that the heads (and tips) of the screwslie in a curved line at a constant radius from a point 338. Preferably,all of the axis of the screws lie in the same plane. Each screw 16preferably extends radially from point 338. The advantage of the curveddiscrete segment 340 is that the tips of screws 16 which are yet to bedriven are spaced further rearward from a workpiece than tips of screwswhich are all in the same straight line. Having the tips of screws 16spaced from the workpiece can be of assistance in preventing the tips ofscrews not yet driven from marking the surface of a workpiece.

A preferred radius of curvature may be in the range of twelve tothirty-six inches. Depending upon the curvature of the segment 340, thescrew feed channel element 76 and its channelway 88 may be adapted tocorrespondingly adopt a similar radius of curvature or have sufficientspace to accommodate both straight and curved strips.

Reference is now made to FIGS. 25 to 28 showing a modified form of acanister 400 to contain a coil of a collated screwstrip 14 and a systemto mount the canister 400 to the driver attachment. In FIGS. 25 to 28,the same reference numbers are used to refer to the same elements as inthe other figures.

FIG. 25 illustrates an exploded view of the housing 18 and slide bodycomponents similar to the view shown in FIG. 2. The individual elementsof the two embodiments are very similar. FIG. 25 shows the use of a noseportion 24 with an enclosed exit opening 86 and with the guide tubehaving the axially extending continuous portion 302 outboard of thepassageway to receive the strip. The support surface 125 is shown to benormal the axis of the guideway.

Reference is made in FIGS. 25 and 26 to the slide stops 25 which aresecured to the rear portion 22 of the slide body by bolts 402 such thatthe slide stops 25 slide in longitudinal slots 40 on each side ofhousing 18 to key the rear portion to the slide body and to prevent theslide body being moved out of the housing past a fully extendedposition.

Each slide stop 25 carries a coupling shoe generally indicated 404 bywhich a canister 400 may be mounted to the the driver attachment. Thecanister 400 is shown in FIGS. 27 and 28 to include a bracket 406 withtwo spaced parallel arms 408 and 410. Each arm 408 and 410 is adapted tobe secured to a coupling shoe 404 on the slide stops 25. In particular,the arms 408 and 410 have slots (not shown) in their inner surfacescomplementary to the shape and profile of the coupling shoe. These slotshave an open forward end and a closed rear end complementary in profileto the curved rear end 412 of the coupling shoe 404. A bolt 414 extendsthrough each of arms 408 and 410 into a nut 416 in each shoe 404 tosecure each arm to its respective shoe 404. Each shoe 404 has alongitudinal rib 418 spaced from the surface of the housing 18 and akeyway in the slots of the arms 408 and 410 is adapted to receive thisrib 418 to positively provide against spreading of the arms apartindependently of the bolts 414. A bolt 415 is provided to secure therear portion 22 to the nose portion 24 with bolt 415 screwing throughthe shoe 404, and the rear portion 22 into the cylindrical portion 77 onthe nose portion 24.

The bracket 406 carrying the canister 400 can readily be removed fromthe slide stops 25, for example, by removing bolts 414 and sliding thearms axially rearward relative the shoes 404.

The bracket 406 has a screw carrying tray 420 coupled to it. A mountingflange 422 on the bracket 406 carries a slide key 424 engaged slidablyin a keyway 426 on the tray 420. By tightening or loosening bolt 428,the tray 420 can be located at desired positions forwardly andrearwardly relative the longitudinal axis of the guideway. The tray ispreferably positioned such that coiled screws sitting with their tips onthe bottom surface 430 of the tray have their heads 17 disposed at thesame plane as heads of screws received in the channelway 88 of the screwfeed channel element 76. The tray has a rearwardly extending side wall431 directing screws to exit via an exit port 432 directly in line tothe channelway 88.

The nose portion 24 and the canister 400 are both coupled to the rearportion 22 and thus move together as parts of the slide body 20. Thetray and screwstrip are always in a constant aligned position relativethe nose portion 24 in all positions in sliding of the slide body 20relative the housing 18. This is in contrast with the cartridge 9 inFIG. 1 which is mounted to the housing 18 and the screwstrip 14 mustflex with each cycle of in and out sliding of the housing 18 relativethe slide body 20.

FIG. 26 shows an advantageous configuration for the shuttle 96 in beingprovided with a fixed post 432 opposed to the manual release arm 102 topermit pivoting of the release arm 102 by drawing the release arm 102towards the fixed post 432 by pinching them between a user′ s thumb andindex finger.

Mounting of the canister 400 to the slide stops 25 permits the slidebody 18 to be fully retractable within the housing without thescrewstrip being flexed in each reciprocal stroke.

As seen in FIG. 26, a stop member 40 is mounted to housing 18 to engagea stop flange 442 on the slide stop 25 and provide increased surfaces tobear stopping load forces. A longitudinal rib 444 extends along the sideof housing 18 and a complementary slotway is provided in each stopflange 442 closely sized thereto to assist in longitudinal parallelsliding and engagement.

Referring to FIGS. 18 and 26, the guide tube 75 has a forward surface446 which is a segment of a spherical surface of a radius centered onthe axis of the guideway such that screws being driven may be driveninto a workpiece a relatively constant distance even if the guideway isdisposed at a slight angle to the normal relative the workpiece.

The preferred slotway illustrated in FIGS. 12 to 22 shows the slotwaybounded forwardly by the ramped surface 308 which slopes relative theaxis of the guideway both forwardly towards the entranceway and withincreased radial distance from the axis of the guideway. It is to beappreciated that the slotway may be bounded forwardly by surfaces normalthe axis of the guideway as, for example, an extension of supportsurface 125 and such a configuration is shown in FIG. 25.

While the invention has been described with reference to preferredembodiment, the invention is not so limited. Many variations andmodifications will now occur to persons skilled in the art. For adefinition of the invention, reference is made to the appended claims.

I claim:
 1. An apparatus for driving with a power driver a screwstripcomprising threaded fasteners such as screws or the like, which arejoined together in a strip comprising: a housing; an elongate driveshaft for operative connection to a power driver for rotation therebyand defining a longitudinal axis; a slide body coupled to the housingfor displacement parallel to the axis of the drive shaft between anextended position and a retracted position; the slide body having (a) aguide channel for said screwstrip extending through said slide body; (b)a guideway to locate successive of the screws advanced via the guidechannel to be axially in alignment with said drive shaft for engagementin driving of the screws from the guideway by the drive shaft; and (c) ascrew feed activation mechanism coupled between the slide body and thehousing whereby displacement of the slide body relative the housingbetween the extended position and the retracted position advancessuccessive screws; the housing comprising a member having a side wallabout a central elongate interior cavity extending longitudinally of themember parallel the axis and open at an open forward end; the side wallhaving two elongate slots therethrough open to the central cavity andextending longitudinally of the interior cavity parallel the axis, theslots located on the side wall at circumferentially spaced locationsgenerally opposite each other relative the axis; two shoe members, eachshoe member slidably received in a respective one of the slots forguided longitudinal sliding parallel the axis guided within itsrespective slot; each shoe member carried by the slide body to guide theslide body in the member for sliding parallel the axis.
 2. An apparatusas claimed in claim 1 wherein: each slot having elongate guide surfaceson each side of the slot extending parallel the axis; each shoe memberhaving side surfaces for bearing on the guide surfaces on each side ofthe slot.
 3. An apparatus as claimed in claim 2 wherein the guidewayextends coaxially through the slide body coaxially about the axis; theguide channel extending transverse to the axis and opening radially intothe guideway on a first side of the guideway to feed successive screwsheld in the screwstrip into the guideway; a screwstrip exitway openingoutwardly from the guideway on a second side of the guideway oppositethe first side via which exitway a strip from which screws have beenremoved by driving with the driver shaft may exit the guideway onadvance of the screwstrip.
 4. An apparatus as claimed in claim 3including an exit slotway in the side wall extending rearwardly from theopen forward end of the member axially in line with the exitway topermit the strip from which screws have been removed to pass unhinderedfrom the exitway through the side wall via the exit slotway when theslide body is retracted relative the housing toward the retractedposition.
 5. An apparatus as claimed in claim 4 including a guidechannel slotway in the side wall extending rearwardly from the openforward end of the member axially in line with the guide channel topermit the guide channel to extend through the side wall via the guidechannel slotway when the slide body is retracted relative the housingtoward the retracted position.
 6. An apparatus as claimed in claim 5wherein the guide channel extends transverse to the axis and away fromthe axis radially farther than the side wall, the slots extend forwardlyto a forward blind end, the open forward end of the member is axiallyforward of the forward blind end of the slots.
 7. An apparatus asclaimed in claim 6 wherein when the slide body is in the extendedposition relative the housing, the guide channel and screwstrip exitwayare forward of the open forward end of the side wall of the member; whenthe slide body is in the retracted position relative the housing, theguide channel and screwstrip exitway are rearward of the open forwardend of the side wall of the member; on retraction of the slide bodyrelative the housing from the extended position, the strap from whichscrews have been driven which extends radially out of the screwstripexitway moves rearwardly in the exit slotway past the open forward endof the side wall of the member and the guide channel moves rearwardly inthe guide channel slotway past the open forward end of the side wall ofthe member.
 8. An apparatus as claimed in claim 2 wherein the housingsubstantially comprises a unitary element injection moulded from aplastic material.
 9. An apparatus as claimed in claim 2 wherein thescrew feed activation mechanism includes a camming surface on thehousing and a cam follower on the slide body; the cam follower engagingthe camming surface whereby in moving between the retracted position andthe extended position the cam follower translates relative axialmovement of the slide body and housing into movement transverse to theaxis.
 10. An apparatus as claimed in claim 9 wherein the screw feedactivation mechanism includes a shuttle carried on the slide bodymovable relative the slide body transverse to the axis; the shuttlecarrying an advance pawl for engagement with the screwstrip to advancethe screwstrip with movement of the shuttle toward the axis; the camfollower coupled to the shuttle to move the shuttle transverse to theaxis with relative movement of the housing and slide body between theretracted position and the extended position.
 11. An apparatus asclaimed in claim 10 wherein the shuttle carried on the slide body forsliding relative the slide body in a linear path transverse to the axis.12. An apparatus as claimed in claim 11 wherein the shuttle is biased tomove toward the axis.
 13. An apparatus as claimed in claim 12 whereinthe advance pawl pivotably mounted to the shuttle for pivoting about apawl axis parallel the axis defined by the drive shaft.
 14. An apparatusas claimed in claim 13 wherein the advance pawl is biased to pivot aboutthe pawl axis into engagement with the screwstrip.
 15. An apparatus asclaimed in claim 1 wherein the shoe members guide the slide body in themember for sliding parallel the axis without relative rotation of theslide body and the member about the axis.
 16. An apparatus as claimed inclaim 15 including: a spring biasing the slide body forwardly relativeto the housing parallel the axis to the extended position.